1. Field of the Invention
Apparatuses consistent with the present invention relate to a multiband antenna with removed coupling. More particularly, the present invention relates to a multiband antenna with removed coupling, which can operate in a plurality of service bands and improve antenna efficiency by removing the coupling.
2. Description of the Related Art
With recent on-going developments of various wireless communication services available through wireless terminals, such as GSM, PSC, WLAN, WiBro, and Bluetooth, reconfigurable antennas are required to enjoy the wireless communication services at one wireless terminal.
To this end, antennas with a very wide frequency band covering a plurality of service bands have been developed. However, an antenna operating in the wide frequency band can reduce the antenna size but may cause noise and interference because of unused bands.
Alternatively, multiband antennas operating in double or multiple frequency bands are under development. Among them, a multiband antenna, which is disclosed in U.S. Patent Application Publication No. 2005-0174294, changes the operating frequency of the antenna by loading a series of PIN diodes in a slot line at intervals and electrically adjusting the length of the radiator through on or off of the PIN diodes. However, such a multiband antenna is relatively large because the slot line is used. To prevent this, the antenna line can be bent in a meander line shape. In this case, the resonant frequency of parasitic effects is generated due to the coupling between the meander lines. The parasitic resonant frequency causes the degradation of the antenna efficiency.
Therefore, what is needed is a solution that can reduce the size of the multiband antenna and/or eliminate the parasitic resonant frequency resulting from the coupling between strip lines.